Communication networks for packet based communication of information in the form of data bits are well known to the person skilled in the art. The growing importance of mobile communication creates the demand to transfer data over wireless connections. The 3rd Generation Partnership Project (3GPP) is a collaboration agreement that brings together a number of telecommunications standards bodies and was established to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks and the radio access technologies that they support. This includes maintenance and development of the Global System for Mobile communication (GSM) Technical Specifications and Technical Reports including evolved radio access technologies (e.g. General Packet Radio Service (GPRS) and Enhanced Data rates for GSM Evolution (EDGE)).
One of the issues that the 3GPP is currently working on is a framework for providing end-to-end Quality of Service for services involving GPRS networks as described in the technical specification 3GPP TS 23.207 V6.2.0 (2004-03). This technical specification describes the use of a Policy Control mechanism in order to control and authorize the use of network resources prior to set-up of a service.
In the future it is assumed that packet switched services undergo Policy Control by means of a Policy Decision Function (PDF). The PDF is a logical element that is used as a logical policy decision element and enables coordination between events in the application layer and resource management in the IP bearer layer.
Policy Control was developed since it is considered important that network managers and service providers can to monitor, control, and enforce the use of network resources and services based on “policies” derived from certain criteria such as the identity/authority level of users and applications, traffic bandwidth requirements, security considerations, time of day/week etc. Because there are varying circumstances in which various entities are entitled to use the services they request, there is a need for rules, need for enforcement methods of these rules, and a need for a “judge” to decide when they apply. Accordingly, three major components of a policy system include policy rules, which are typically stored in a policy database, policy enforcement, which may be implemented at Policy Enforcement Points (PEP), and Policy Decision Points. The IETF has standardized a protocol for information exchange between PEPs and Policy Decision Points under the term Common Open Policy Service (COPS). In general, a policy may be regarded as a collection of rules that result in one or more actions when specific conditions exist.
FIG. 1 is a schematic block diagram that illustrates the different elements that are involved in the policy control mechanism developed by 3GPP. FIG. 1 illustrates an example where a service is set-up between a mobile User Equipment (UE) 1 and an Application Function (AF) of a service provider. The UE includes an AF Client 3 which communicates with the AF 2 by means of AF session signaling 4 in order to initiate an application session. The set-up of the session and activation of the service require set-up of a bearer service to carry the data packets of the session. The session may include one or a plurality of different IP flows with specific requirements for bearer resources. The AF session signaling 4 may include information on Quality of Service (QoS) requirements which are translated into bearer QoS parameters by a translation/mapping function 5 in the UE. In order to activate the bearer service the UE sends a request for activation of a PDP context with the bearer QoS parameters that are determined by the translation/mapping function to a GGSN 6. The communication between the UE and the GGSN is in this example handled by means of UMTS BS Managers 7, 8 in the UE and the GGSN respectively. In this example the GGSN functions as a PEP and is provided with an IP BS Manager 9 which is involved in QoS management. The GGSN 6 interacts with a PDF 10, via a Go interface 11, in order to execute policy control. The PDF 10 makes policy decisions based on policy set-up information obtained from the AF 2 via a Gq interface 12. More detailed information regarding the elements illustrated in FIG. 1 and their function can be found in the above mentioned technical specification TS 23.207 V6.2.0.
When 3GPP specified the policy control mechanism an authorization token was also introduced in order to establish a binding mechanism for mapping PDP contexts and IP flows to policy information. The authorization token is generated by the PDF for a particular AF session on request from the AF. The authorization token includes a fully qualified domain name of the PDF and is unique across all PDP contexts associated with an APN (Access Point Name). The AF sends the authorization token to the UE in the AF session signalling. The UE should then include the applicable authorization token in any request to activate or modify a PDP context. The authorization token will then be used in the GGSN and PDF to map to the correct policy information.
The plan to introduce the authorization token and the associated handling of it when implementing policy control in 3G systems has a number of disadvantages. One major disadvantage is that it requires modification of existing UEs in order to make them capable to handle authorization tokens. Another disadvantage is that the introduction of the authorization token requires new standardization for the RTSP (Real-Time Streaming Protocol), SIP (Session Initiation Protocol), and SDP (Session Description Protocol) and other protocols used in set-up and handling of application sessions.